| Summary: | Sponges of the Latrunculiidae family produce bioactive pyrroloiminoquinone alkaloids including makaluvamines, discorhabdins, and tsitsikammamines. The aim of this study was to use LC-ESI-MS/MS-driven molecular networking to characterize the pyrroloiminoquinone secondary metabolites produced by six latrunculid species. These are <i>Tsitsikamma favus</i>, <i>Tsitsikamma pedunculata</i>, <i>Cyclacanthia bellae,</i> and <i>Latrunculia apicalis</i> as well as the recently discovered species, <i>Tsitsikamma nguni</i> and <i>Tsitsikamma michaeli</i>. Organic extracts of 43 sponges were analyzed, revealing distinct species-specific chemical profiles. More than 200 known and unknown putative pyrroloiminoquinones and related compounds were detected, including unprecedented makaluvamine-discorhabdin adducts and hydroxylated discorhabdin I derivatives. The chemical profiles of the new species <i>T. nguni</i> closely resembled those of the known <i>T. favus</i> (chemotype I), but with a higher abundance of tsitsikammamines vs. discorhabdins. <i>T. michaeli</i> sponges displayed two distinct chemical profiles, either producing mostly the same discorhabdins as <i>T. favus</i> (chemotype I) or non- or monobrominated, hydroxylated discorhabdins. <i>C. bellae</i> and <i>L. apicalis</i> produced similar pyrroloiminoquinone chemistry to one another, characterized by sulfur-containing discorhabdins and related adducts and oligomers. This study highlights the variability of pyrroloiminoquinone production by latrunculid species, identifies novel isolation targets, and offers fundamental insights into the collision-induced dissociation of pyrroloiminoquinones.
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